This invention relates to implements used to cut heavy sheet or web materials (e.g., floor coverings, plastic, leather, etc.).
While a variety of arrangements to support and clamp such replaceable blades have been proposed, each has involved one or more of various drawbacks, especially when used to cut relatively heavy materials. Thus, for example, those employing a screw or bolt to hold the blade against a support surface have often necessitated the use of a tool (e.g., a wrench or screwdriver) thus resulting in a cumbersome and time-consuming operation and, additionally, frequently resulting in the stripping of threads thus requiring replacement of parts or discarding of the knife. Other approaches have involved the use of a knurled or wing nut to permit manual tightening. These designs have frequently made it impossible to apply sufficient force to securely clamp the blade, have included nut portions projecting from the knife in various directions making use of the knife difficult in various circumstances, and require considerable manual dexterity in attempting to simultaneously tighten the nut (requiring the full use of one hand) while holding the support unit and positioning the still-loose blade thereon. Additionally, the flexibility of the blade-contacting members, while facilitating blade insertion and removal, has resulted in inadequate blade support in the cutting of heavy materials (e.g., carpet).